Question in the picture! I just want to know if my answer is correct!

If i have one apple and give you the apple, how many apples do i have?

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

Lana's family entered a 5-kilometer race lana's average step length is about 0.5 meter how many steps will she need to take the finish